Milestones:
    1. Create two paddles (DONE)
    2. Move paddles (DONE)
    3. Add collision detection to paddles on walls (DONE)
    4. Create ball and move it in a random direction when it spawns (DONE)
    5. Add collision detection to ball on upper and lower walls (DONE)
    6. Add collision detection to ball on paddles (DONE)
    7. Restart position of ball when it goes past either of the paddles' goal field (DONE)
    8. Refactor code (DONE)
    9. Add scoring system (DONE)
    10. Temporarily freeze ball every start of a round (DONE)
    11. Allow game restart
    12. Add dynamics to gameplay -- e.g. implement acceleration
    12. Create game menu -- vs Human or vs AI
    13. Implement AI